Air filters are known to use a fan to generate a flow of air through a solid filtration medium. Whilst such filters are successful, a relatively large fan is required to overcome the pressure drop across the filter, resulting in a device which is relatively noisy and consumes a relatively large quantity of energy.
A number of air cleaners are known which generate a mist of water to trap entrained particles in air. These include U.S. Pat. No. 7,115,155 with a rotating tube, the bottom end of which is positioned in a reservoir. The tube has a number of openings through which water is sprayed under centrifugal force as the tube is rotated. This generates a mist through which a stream of air is passed for cleaning.
U.S. Pat. No. 6,656,253 uses an ultrasonic atomiser to generate a mist. The mist of particles is charged to attract the entrained particles in a flow of air. The stream of charged particles and entrained contaminants is then passed through a collecting surface which traps the contaminants.
WO 02/077537 discloses a distributor to generate a spray of droplets which trap airborne contaminants. The dirty stream is then passed through a UV chamber and filter to remove the contaminants before the water is re-circulated.
The present invention aims to provide a simple low cost device with low energy consumption which is suitable for domestic use and which can readily be maintained by the user.